Electronic device and method of manufacturing semiconductor device

ABSTRACT

There is provided an electronic device including at least a first electrode, a second electrode disposed to be spaced apart from the first electrode, and an active layer disposed over the second electrode from above the first electrode and formed of an organic semiconductor material. A charge injection layer is formed between the first electrode and the active layer and between the second electrode and the active layer, and the charge injection layer is formed of an organic material having an increased electric conductivity when the charge injection layer is oxidized.

BACKGROUND

The present disclosure relates to an electronic device and a method ofmanufacturing a semiconductor device.

Currently, a field effect transistor (FET) including a thin filmtransistor (TFT) used in a variety of electronic equipment is configuredof, for example, a channel formation region and source/drain electrodesformed in a substrate such as a silicon semiconductor substrate or asilicon semiconductor material layer, a gate insulating layer includingSiO₂ formed on a surface of the substrate, and a gate electrode disposedto face the channel formation region with the gate insulating layer. Inaddition, such an FET is simply referred to as a top-gate type FET.Alternatively, the FET is configured by a gate electrode disposed on asupport, a gate insulating layer disposed on the support including thegate electrode and including SiO₂, and a channel formation region andsource/drain electrodes formed on the gate insulating layer. Inaddition, such an FET is simply referred to as a bottom-gate type FET. Avery expensive device for manufacturing a semiconductor device is usedto manufacture the FET having the structure described above, and it isthus necessary to reduce the manufacturing cost.

Among these, recently, electronic devices having an active layer formedof an organic semiconductor material have been actively developed, andin particular, organic electronic devices (which may be simply referredto hereinafter as organic devices) such as organic transistors, organiclight emitting elements, or organic solar cells are attractingattention. The ultimate goal of these organic devices may be to have alow cost, a light weight, flexibility, and high performance. Whencompared with inorganic materials of which silicon is a prime example,the organic semiconductor material (1) allows a large-sized organicdevice to be manufactured at a low cost at a low temperature in a simpleprocess, (2) allows the organic device having the flexibility to bemanufactured, and (3) allows performance or a physical property of theorganic device to be controlled by modifying molecules constituting theorganic semiconductor material to a desired form. The organicsemiconductor material thus has such various advantages.

Accordingly, many materials having high performance such as highreliability as the organic semiconductor material have been developed.However, there is a typical problem that efficiency of injecting chargesinto the active layer from a metal material for forming electrodes suchas source/drain electrodes is not so high.

In light of the foregoing problem, for example, techniques of forming acharge injection layer between source/drain electrodes and a channelformation region are disclosed in Japanese Laid-Open Patent PublicationNo. 2006-253675 and Japanese Laid-Open Patent Publication No.2005-327797.

SUMMARY

However, in the technique disclosed in Japanese Laid-Open PatentPublication No. 2006-253675, the charge injection layer is formed of amaterial having a work function between a work function of the metalmaterial for forming the source/drain electrodes and an ionizationpotential of the organic semiconductor material. That is, this techniqueis charge injection based on the premise of a so-called hoppingconductivity. For this reason, it is difficult for the technique to be afundamental solution for reducing a contact resistance between thesource/drain electrodes and the channel formation region. In addition,in the technique disclosed in Japanese Laid-Open Patent Publication No.2005-327797, the charge injection layer is formed of an inorganicmaterial, but it is necessary to form a thin film with high accuracyusing a plurality of raw materials. In addition, film formationequipment becomes larger, and the film formation is necessarilytime-consuming.

The present disclosure thus provides an electronic device having acharge injection layer and a method of manufacturing a semiconductordevice that can be formed in a short time using a simple device and thatcan reliably reduce a contact resistance between an electrode and anactive layer.

According to first to sixth aspects of the present disclosure, there isprovided an electronic device which includes at least: a firstelectrode; a second electrode disposed to be spaced apart from the firstelectrode; and an active layer disposed over the second electrode fromabove the first electrode and formed of an organic semiconductormaterial, and a charge injection layer is formed between the firstelectrode and the active layer and between the second electrode and theactive layer. The charge injection layer is formed of an organicmaterial having an increased electric conductivity when the chargeinjection layer is oxidized (electronic device according to the firstaspect of the present disclosure), an oxide of a Weitz typeoxidation-reduction based organic compound (electronic device accordingto the second aspect of the present disclosure), an oxide of an organiccompound having a cyclic structure in which the number of π electrons is4n+3 (n is a positive integer) (electronic device according to the thirdaspect of the present disclosure), an oxide of an organic compoundhaving a dichalcogen five-membered ring (electronic device according tothe fourth aspect of the present disclosure), an oxide of an organiccompound having a monochalcogen six-membered ring (electronic deviceaccording to the fifth aspect of the present disclosure), or an oxide ofat least one organic compound selected from the group includingtetrathiafulvalene (TTF) and derivatives thereof, tetrathiapentalene andderivatives thereof, tetrathiatetracene, hexathiopentacene, pyranylideneand derivatives thereof, and bithiapyrinylidene (material in whichoxygen O of pyranylidene is substituted with sulfur S) and derivativesthereof (electronic device according to the sixth aspect of the presentdisclosure).

According to the first or second aspect of the present disclosure, thereis provided a method of manufacturing a semiconductor device that is amethod of manufacturing a so-called bottom gate-bottom contact typesemiconductor device, the method including: (A) forming a gate electrodeon a base, and then forming a gate insulating layer on the base and thegate electrode; (B) forming a pair of source/drain electrodes on thegate insulating layer; and (C) forming a channel formation region formedof an organic semiconductor material on the gate insulating layerdisposed between the pair of source/drain electrodes and additionallyforming a channel formation region extension formed of the organicsemiconductor material above each of the source/drain electrodes. Themethod further includes: between processes (B) and (C), forming a chargeinjection layer-precursor layer formed of an organic compound on each ofthe source/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer havinga higher electric conductivity than the charge injection layer-precursorlayer (method of manufacturing the semiconductor device according to thefirst aspect of the present disclosure), or the method further includes:between processes (B) and (C), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer,wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring (method ofmanufacturing the semiconductor device according to the second aspect ofthe present disclosure).

According to the third or fourth aspect of the present disclosure, thereis provided a method of manufacturing a semiconductor device that is amethod of manufacturing a so-called bottom gate-top contact typesemiconductor device, the method including: (A) forming a gate electrodeon a base, and then forming a gate insulating layer on the base and thegate electrode; (B) forming a channel formation region and a channelformation region extension formed of an organic semiconductor materialon the gate insulating layer; and (C) forming a pair of source/drainelectrodes above the channel formation region extension. The methodfurther includes: between processes (B) and (C), forming a chargeinjection layer-precursor layer formed of an organic compound on thechannel formation region extension, and then performing oxidation on thecharge injection layer-precursor layer to form a charge injection layerhaving a higher electric conductivity than the charge injectionlayer-precursor layer (method of manufacturing the semiconductor deviceaccording to the third aspect of the present disclosure), or the methodfurther includes: between processes (B) and (C), forming a chargeinjection layer-precursor layer formed of an organic compound on thechannel formation region extension, and then performing oxidation on thecharge injection layer-precursor layer to form a charge injection layer,wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring (method ofmanufacturing the semiconductor device according to the fourth aspect ofthe present disclosure).

According to the fifth or sixth aspect of the present disclosure, thereis provided a method of manufacturing a semiconductor device that is amethod of manufacturing a so-called top gate-bottom contact typesemiconductor device, the method including: (A) forming a pair ofsource/drain electrodes on a base; (B) forming a channel formationregion formed of an organic semiconductor material between the pair ofsource/drain electrodes and additionally forming a channel formationregion extension formed of the organic semiconductor material above eachof the source/drain electrodes; and (C) forming a gate insulating layeron the channel formation region and the channel formation regionextension, and then forming a gate electrode on a portion of the gateinsulating layer on the channel formation region. The method furtherincludes: between processes (A) and (B), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer havinga higher electric conductivity than the charge injection layer-precursorlayer (method of manufacturing the semiconductor device according to thefifth aspect of the present disclosure), or the method further includes:between processes (A) and (B), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer,wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring (method ofmanufacturing the semiconductor device according to the sixth aspect ofthe present disclosure).

According to the seventh or eighth aspect of the present disclosure,there is provided a method of manufacturing a semiconductor device thatis a method of manufacturing a so-called top gate-top contact typesemiconductor device, the method including: (A) forming a channelformation region and a channel formation region extension formed of anorganic semiconductor material on a base; (B) forming a pair ofsource/drain electrodes above the channel formation region extension;and (C) forming a gate insulating layer on the channel formation regionand the pair of source/drain electrodes, and then forming a gateelectrode on a portion of the gate insulating layer on the channelformation region. The method further includes: between processes (A) and(B), forming a charge injection layer-precursor layer formed of anorganic compound on the channel formation region extension, and thenperforming oxidation on the charge injection layer-precursor layer toform a charge injection layer having a higher electric conductivity thanthe charge injection layer-precursor layer (method of manufacturing thesemiconductor device according to the seventh aspect of the presentdisclosure), or the method further includes: between processes (A) and(B), forming a charge injection layer-precursor layer formed of anorganic compound on the channel formation region extension, and thenperforming oxidation on the charge injection layer-precursor layer toform a charge injection layer, wherein the organic compound includes atleast one organic compound selected from the group including a Weitztype oxidation-reduction based organic compound, an organic compoundhaving a cyclic structure in which the number of π electrons is 4n+3 (nis a positive integer), an organic compound having a dichalcogenfive-membered ring, and an organic compound having a monochalcogensix-membered ring (method of manufacturing the semiconductor deviceaccording to the eighth aspect of the present disclosure).

In the electronic device according to the first to sixth aspects of thepresent disclosure, since the charge injection layer is formed betweenthe first electrode and the active layer and between the secondelectrode and the active layer and the organic compound for forming thecharge injection layer is defined, it is possible to form the chargeinjection layer in a short time using a simple device and to reliablyreduce the contact resistance between the electrodes and the activelayer. In addition, in the method of manufacturing the semiconductordevice according to the first to eighth aspects of the presentdisclosure, since the organic compound for forming the charge injectionlayer is defined and oxidation can be performed on the charge injectionlayer-precursor layer to obtain the charge injection layer, it ispossible to form the charge injection layer in a short time using asimple device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1D are partial cross-sectional views of a base or the likeschematically illustrating a method of manufacturing a semiconductordevice of a first embodiment;

FIGS. 2A to 2D are partial cross-sectional views of a base or the likeschematically illustrating a method of manufacturing a semiconductordevice of a second embodiment;

FIGS. 3A to 3D are partial cross-sectional views of a base or the likeschematically illustrating a method of manufacturing a semiconductordevice of a third embodiment;

FIGS. 4A to 4D are partial cross-sectional views of a base or the likeschematically illustrating a method of manufacturing a semiconductordevice of a fourth embodiment;

FIGS. 5A to 5D are partial cross-sectional views of a base or the likeschematically illustrating a method of manufacturing a semiconductordevice of a fifth embodiment;

FIGS. 6A to 6D are partial cross-sectional views of a base or the likeschematically illustrating a method of manufacturing a semiconductordevice of a sixth embodiment;

FIGS. 7A to 7C are partial cross-sectional views of a base or the likeschematically illustrating a method of manufacturing a semiconductordevice of a seventh embodiment;

FIGS. 8A and 8B are partial cross-sectional views schematicallyillustrating a two-terminal type electronic device of an eighthembodiment;

FIG. 9 is a diagram illustrating a state in which tetrathiafulvalene(TTF) is oxidized;

FIG. 10 is a graph illustrating a result of measuring values of contactresistances in the first embodiment and a comparative example; and

FIG. 11 is a graph illustrating a measurement result of effectivemobility in the first embodiment and the comparative example.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Hereinafter, embodiments of the present disclosure will be describedwith reference to drawings, but the present disclosure is not limited tothe embodiments, and various values or materials of the embodiments aremerely illustrative. Further, the description will be made in thefollowing order.

1. Electronic device according to the first to sixth aspects of thepresent disclosure, method of manufacturing semiconductor deviceaccording to the first to eighth aspects of the present disclosure, andgeneral description

2. First embodiment (electronic device according to the first to sixthaspects of the present disclosure and method of manufacturingsemiconductor device according to the first and second aspects of thepresent disclosure)

3. Second embodiment (electronic device according to the first to sixthaspects of the present disclosure and method of manufacturingsemiconductor device according to the third and fourth aspects of thepresent disclosure)

4. Third embodiment (modification of the second embodiment)

5. Fourth embodiment (another modification of the second embodiment)

6. Fifth embodiment (electronic device according to the first to sixthaspects of the present disclosure and method of manufacturingsemiconductor device according to the fifth and sixth aspects of thepresent disclosure)

7. Sixth embodiment (electronic device according to the first to sixthaspects of the present disclosure and method of manufacturingsemiconductor device according to the seventh and eighth aspects of thepresent disclosure)

8. Seventh embodiment (modification of the sixth embodiment)

9. Eighth embodiment (modification of the fifth or sixth embodiment),etc.

[Electronic Device According to the First to Sixth Aspects of thePresent Disclosure, Method of Manufacturing Semiconductor DeviceAccording to the First to Eighth Aspects of the Present Disclosure, andGeneral Description]

In the method of manufacturing a semiconductor device according to thefirst to eighth aspects of the present disclosure, oxidation performedon a charge injection layer-precursor layer may be in the form ofnatural oxidation (including heat-treating the charge injectionlayer-precursor layer) under an air atmosphere, or may be in the form ofoxidation (including heat-treating the charge injection layer-precursorlayer) under an oxygen gas atmosphere (or under an oxidationatmosphere).

The electronic device of the present disclosure may have a so-calledthree-terminal structure or a two-terminal structure. In the formercase, the electronic device further includes an insulating layer, and acontrol electrode disposed to face a portion of an active layer locatedbetween the first and second electrodes via the insulating layer. Forexample, the electronic device having the three-terminal structureincludes a field effect transistor (FET), in particular, a thin filmtransistor (TFT), or a light emitting element. That is, the lightemitting element (organic light emitting element and organic lightemitting transistor) may include the active layer that emits light bymeans of voltage applied to the control electrode and the first andsecond electrodes. In these electronic devices, a current flowing in theactive layer from the first electrode toward the second electrode iscontrolled by the voltage applied to the control electrode. Here, in thelight emitting element, an organic semiconductor material for formingthe active layer has a function of accumulating charges by means ofmodulation based on the voltage applied to the control electrode or afunction of emitting light on the basis of recombination betweeninjected electrons and positive holes (holes), and the emissionintensity is in proportion to an absolute value of the current flowingfrom the first electrode toward the second electrode, and can bemodulated by the voltage applied to the control electrode and thevoltage applied between the first and second electrodes. In addition,whether the electronic device fulfills a function as the FET or acts asthe light emitting element depends on a state (bias) of the voltageapplied to the first and second electrodes. First, the bias in a rangethat does not cause electrons to be injected from the second electrodeis applied and then the control electrode is modulated, thereby causingthe current to flow from the first electrode toward the secondelectrode. This is the transistor operation. On the other hand, whenholes are sufficiently accumulated and then the bias applied to thefirst and second electrodes is increased, electrons start to beinjected, thereby causing the electrons to be recombined with the holesto emit light. In addition, as the electronic device having thetwo-terminal structure, a photoelectric conversion element in which thecurrent flows between the first and second electrodes by means of lightirradiation toward the active layer may be employed. In particular, whenthe electronic device includes a photoelectric conversion element, thephotoelectric conversion element may include a solar cell or an imagesensor. In addition, the electronic device having the three-terminalstructure may also include the photoelectric conversion element. In thiscase, the voltage may not be applied or may be applied to the controlelectrode. In the latter case, the voltage applied to the controlelectrode allows the flowing current to be modulated.

In the electronic device according to the first to sixth aspects of thepresent disclosure including the preferred forms and configurationsdescribed above, the electronic device may be a bottom gate-bottomcontact type TFT, a bottom gate-top contact type TFT, a top gate-bottomcontact type TFT, or a top gate-top contact type TFT.

In particular, when the electronic device according to the first tosixth aspects of the present disclosure is the bottom gate-bottomcontact type TFT having the three-terminal structure, the controlelectrode is formed on the base as a gate electrode, the insulatinglayer is formed on the gate electrode and the base as a gate insulatinglayer, the first and second electrodes are formed on the gate insulatinglayer as a pair of source/drain electrodes, the active layer is formedon the gate insulating layer between the pair of source/drain electrodesas a channel formation region and formed above the source/drainelectrodes as a channel formation region extension, and a chargeinjection layer is formed between each of the source/drain electrodesand the channel formation region extension.

In addition, when the electronic device according to the first to sixthaspects of the present disclosure is the bottom gate-top contact typeTFT having the three-terminal structure, the control electrode is formedon the base as a gate electrode, the insulating layer is formed on thegate electrode and the base as a gate insulating layer, the active layeris formed on the gate insulating layer as a channel formation region anda channel formation region extension, the first and second electrodesare formed above the channel formation region extension as a pair ofsource/drain electrodes, and a charge injection layer is formed betweeneach of the source/drain electrodes and the channel formation regionextension.

In addition, when the electronic device according to the first to sixthaspects of the present disclosure is the top gate-bottom contact typeTFT having the three-terminal structure, the first and second electrodesare formed on the base as a pair of source/drain electrodes, the activelayer is formed on the base between the pair of source/drain electrodesas a channel formation region and is formed above the source/drainelectrodes as a channel formation region extension, the insulating layeris formed on the channel formation region and the channel formationregion extension as a gate insulating layer, the control electrode isformed on the gate insulating layer to face the channel formation regionas a gate electrode, and a charge injection layer is formed between eachof the source/drain electrodes and the channel formation regionextension.

In addition, when the electronic device according to the first to sixthaspects of the present disclosure is the top gate-top contact type TFThaving the three-terminal structure, the active layer is formed on thebase as a channel formation region and a channel formation regionextension, the first and second electrodes are formed above the channelformation region extension as a pair of source/drain electrodes, theinsulating layer is formed on the pair of source/drain electrodes andthe channel formation region as a gate insulating layer, the controlelectrode is formed on the gate insulating layer as a gate electrode,and a charge injection layer is formed between each of the source/drainelectrodes and the channel formation region extension.

In the electronic device according to the sixth aspect of the presentdisclosure, the charge injection layer includes at least one oxide of anorganic compound selected from the group including tetrathiafulvaleneand derivatives thereof, tetrathiapentalene and derivatives thereof,tetrathiatetracene, hexathiopentacene, pyranylidene and derivativesthereof, and bithiapyrinylidene and derivatives thereof. Here, as thederivatives of tetrathiafulvalene (TTF), in particular, MDT-TTF, TMSF,BMDT-TTF, BEDO-TTF, BEDT-TTF, DMB EDT-TTF, TM-TTF, BEDT-TSF, DMET, andso forth may be employed. As the derivative of tetrathiapentalene, inparticular, TTM-TTP, BEDT-TTP, CnTTM-TTP, and so forth may be employed.As the derivatives of tetrathiapentalene, in particular,dithiapyranylidene or the like may be employed. In addition, the organiccompound for forming the charge injection layer of the electronic deviceaccording to the sixth aspect of the present disclosure may be employedas a specific example of a Weitz type oxidation-reduction based organiccompound of the electronic device according to the second aspect of thepresent disclosure. In addition, the organic compound for forming thecharge injection layer of the electronic device according to the sixthaspect of the present disclosure may be employed as a specific exampleof an organic compound having a cyclic structure in which a number of πelectrons is 4n+3 (n is a positive integer) in the electronic deviceaccording to the third aspect of the present disclosure. In addition,TTF and derivatives thereof, tetrathiapentalene and derivatives thereof,tetrathiatetracene, and hexathiopentacene may be employed as specificexamples of organic compounds having dichalcogen five-membered rings ofthe electronic device according to the fourth aspect of the presentdisclosure. In addition, pyranylidene and derivatives thereof, andbithiapyrinylidene and derivatives thereof may be employed as specificexamples of organic compounds having monochalcogen six-membered rings ofthe electronic device according to the fifth aspect of the presentdisclosure.

As a method of forming the charge injection layer-precursor layer, acoating method may be employed. Here, as the coating method, variousprinting methods such as a screen printing method, an inkjet printingmethod, an offset printing method, a reverse offset printing method, agravure printing method, a gravure offset printing method, a reliefprinting method, a flexo printing method, a microcontact method; a spincoating method; various coating methods such as an air doctor coatermethod, a blade coater method, a rod coater method, a knife coatermethod, a squeeze coater method, a reverse roll coater method, atransfer roll coater method, a gravure coater method, a kiss coatermethod, a cast coater method, a spray coater method, a slit coatermethod, a slit orifice coater method, a calender coater method, acasting method, a capillary coater method, a bar coater method, adipping method; a spray method; a method using a dispenser; and a methodof coating a liquid material such as a stamp method may be employed. Inaddition, the method of forming the charge injection layer-precursorlayer is not limited to the coating methods but may employ physicalvapor deposition (PVD) methods such as resistive heating evaporationmethods, sputtering methods, or vacuum evaporation methods. For example,the charge injection layer-precursor layer or the charge injection layermay be formed on the basis of well-known methods such as a wet etchingmethod, a dry etching method, or a laser ablation method as necessary.

In the electronic device according to the first aspect of the presentdisclosure and the method of manufacturing the semiconductor deviceaccording to the first, third, fifth and seventh aspects of the presentdisclosure, as a relation between the value σ₁ of the electricconductivity (also referred to as electrical conductivity orconductivity) of the organic compound for forming the charge injectionlayer-precursor layer and the value σ₂ of the electric conductivity ofthe organic compound for forming the charge injection layer obtained byperforming oxidation on the charge injection layer-precursor layer, forexample, σ₂/σ₁≧100/1 may be employed. The electric conductivity may bemeasured on the basis of methods such as IV measurement on two terminalsor sheet resistance measurement on four terminals.

In the electronic device according to the first to sixth aspects of thepresent disclosure and the method of manufacturing the semiconductordevice according to the first to eighth aspects of the presentdisclosure including various preferred embodiments and configurationsdescribed above (these may be simply referred to as the presentdisclosure), as the organic semiconductor material, for example,polypyrrole and substitutes of polypyrrole, polythiophene andderivatives of polythiophene, isothianaphthenes such aspolyisothianaphthene, thienylenevinylenes such as polythienylenevinylene, types of poly(p-phenylenevinylene) such aspoly(p-phenylenevinylene), polyaniline and derivatives of polyaniline,polyacetylene, polydiacetylene, polyazulene, polypyrene, polycarbazole,polyselenophene, polyfuran, poly(p-phenylene), polyindole,polypyridazine, naphthacene, pentacenel[2,3,6,7-dibenzanthracene],hexacene, heptacene, dibenzopentacene, tetrabenzopentacene, pyrene,benzopyrene, dibenzopyrene, chrysene, perylene, coronene, terylene,ovalene, quaterrylene, acenes such as circumanthracene, and derivativesin which some carbon atoms of an acene are substituted with atoms suchas N, S, or O, or a functional group such as a carbonyl group(dioxaanthanthrene based compounds including perixanthenoxanthene andderivatives of perixanthenoxanthene, triphenoldioxazine,triphenoldithiazine, hexacene-6,15-quinone), polymers such aspolyvinylcarbazole, polyphenylene sulfide, or polyvinylene sulfide, orpolycyclic condensation products may be employed. Alternatively,oligomers having these polymers as repeating units may be employed. Inaddition, metal phthalocyanines represented by copper phthalocyanine,naphthalene 1,4,5,8-tetracarboxylic acid diimide,N,N-bis(4-trifluoromethylbenzyl)naphthalene 1,4,5,8-tetracarboxylic aciddiimide, N,N′-bis(1H,1H-perfluorooctyl), N,N′-bis(1H,1H-perfluorobutyl),N,N′-dioctylnaphthanlene 1,4,5,8-tetracarboxylic acid diimidederivatives, naphthalene tetracarboxylic acid diimides such asnaphthalene 2,3,6,7 tetracarboxylic acid diimide, condensed ringtetracarboxylic acid diimides such as anthracene tetracarboxylic aciddiimide such as anthracene 2,3,6,7-tetracarboxylic acid diimide,fullerenes such as C60, C70, C76, C78, or C84, carbon nanotubes such asSWNT, or pigments such as merocyanine pigment or hemicyanine pigment maybe employed. Alternatively, as the organic semiconductor material,poly-3-hexylthiophene [P3HT] in which a hexyl group is introduced intopolythiophene, polyanthracene, triphenylene, polytellurophene,polynaphthalene, polyethylenedioxythiophene,poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid [PEDOT/PSS],or quinacridone may be employed. Alternatively, as the organicsemiconductor material, compounds selected from the group includingcondensed polycyclic aromatic compounds, porphyrin based derivatives,phenylvinylidene based conjugated oligomers, and thiophene basedconjugated oligomers may be employed. In particular, for example,condensed polycyclic aromatic compounds such as acene-based molecules(pentacene, tetracene, and so forth), porphyrin based molecules, and(phenylvinylidene based or thiophene based) conjugated oligomers may beemployed. Alternatively, as the organic semiconductor material, forexample, porphyrin, 4,4′-biphenyldithiol (BPDT),4,4′-diisocyanobiphenyl, 4,4′-diisocyano-p-terphenyl,2,5-bis(5′-thioacetyl-2′-thiophenyl)thiophene,2,5-bis(5′-thioacetoxyl-2′-thiophenyl)thiophene, 4,4′-diisocyanophenyl,benzidine(biphenyl-4,4′-diamine), tetracyanoquinodimethane (TCNQ),TTF-TCNQ complex, bisethylenetetrathiafulvalene (BEDTTTF)-perchloricacid complex, BEDTTTF-iodine complex, charge transfer complexesrepresented by TCNQ-iodine complex, biphenyl-4,4′-dicarboxylic acid,1,4-di(4-thiophenylacetylenyl)-2-ethylbenzene,1,4-di(4-isocyanophenylacetylenyl)-2-ethylbenzene, dendrimer,1,4-di(4-thiophenylacetylenyl)-2-ethylbenzene,2,2″-dihydroxy-1,1′:4′,1″-terphenyl, 4,4′-biphenyldiethanal,4,4′-biphenyldiol, 4,4′-biphenyldiisocyanate, 1,4-diacetylbenzene,diethylbiphenyl-4,4′-dicarboxylate,benzo[1,2-c;3,4-c′;5,6-c″]tris[1,2]dithiol-1,4,7-trithione,alpha-sexithiophene, tetrathiotetracene, tetraselenotetracene,tetratellurotetracene, poly(3-alkylthiophene),poly(3-thiophene-β-ethanesulfonic acid), poly(N-alkylpyrrole)poly(3-alkylpyrrole), poly(3,4-dialkylpyrrole),poly(2,2′-thienylpyrrole), or poly(dibenzothiophene sulphide) may beemployed.

In addition, as a preferred combination (of the organic semiconductormaterial and the material for forming the charge injectionlayer-precursor layer), a derivative of perixanthenoxanthene and aderivative of TTF, pentacene and a derivative of TTF, and so forth maybe employed.

A polymer may be included in the active layer, the channel formationregion, or the channel formation region extension (organic semiconductormaterial layer) as necessary. The polymer may be dissolved in an organicsolvent. In particular, as the polymer (organic binder, binder),polystyrene, polyalphamethylstyrene, or polyolefin may be employed. Inaddition, in some cases, an additive (e.g., a so-called doping materialsuch as n-type impurities or p-type impurities) may be added.

As a solvent for preparing the organic semiconductor material solution,aromatics such as toluene, xylene, mesitylene, and tetralin; ketonessuch as cyclopentanone, and cyclohexanone; and hydrocarbons such asdecalin may be employed. Above all, it is preferable that solventshaving a relatively high boiling point such as mesitylene, tetralin, anddecalin be used in terms of transistor characteristics and also in termsof preventing the organic semiconductor material from being rapidlydried at the time of forming the organic semiconductor material layer.

As a method of forming the active layer or the channel formation regionand the channel formation region extension, a coating method may beemployed. However, the present disclosure is not limited thereto but mayemploy various PVD methods or CVD methods to form the active layer orthe channel formation region and the channel formation region extension.Here, the coating method may be any of general coating methods withoutproblem. In particular, for example, the various coating methodsdescribed above may be employed. The channel formation region and thechannel formation region extension may be patterned on the basis ofwell-known methods such as a wet etching method or a dry etching methodand a laser ablation method as necessary. In addition, when the chargeinjection layer-precursor layer is formed on the channel formationregion extension, a protective layer may be formed on the channelformation region and the charge injection layer-precursor layer may thenbe formed on the channel formation region extension and the protectivelayer as necessary. In addition, although the charge injectionlayer-precursor layer on the protective layer or the charge injectionlayer is removed in the end, the protective layer is present when thecharge injection layer-precursor layer or the charge injection layer isremoved, and it is thus possible to reliably prevent the channelformation region from being damaged.

As a material for forming the control electrode, the first electrode,the second electrode, the gate electrode, or the source/drainelectrodes, metals such as platinum (Pt), gold (Au), palladium (Pd),chromium (Cr), molybdenum (Mo), nickel (Ni), aluminum (Al), silver (Ag),tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In),tin (Sn), iron (Fe), cobalt (Co), zinc (Zn), magnesium (Mg), manganese(Mn), ruthenium (Rh), or rubidium (Rb), or alloys including thesemetallic elements, conductive particles including these metals,conductive particles of alloys including these metals, or conductivematerials such as polysilicon containing impurities may be employed, anda stacked structure of layers including these elements may also beemployed. In addition, as a material for forming the control electrode,the first electrode, the second electrode, the gate electrode, or thesource/drain electrodes, organic materials (conductive high molecules)such as PEDOT/PSS, TTF-TCNQ, or polyaniline may be employed. Thematerial for forming the control electrode, the first electrode, thesecond electrode, the gate electrode, or the source/drain electrodes maybe the same material or different materials.

As a method of forming the control electrode, the first electrode, thesecond electrode, the gate electrode, or the source/drain electrodes,although also depending on the material for forming these electrodes,any one of the coating methods listed above, a physical vapor deposition(PVD) method, a pulse laser deposition (PLD) method, an arc dischargemethod, various chemical vapor deposition (CVD) methods including metalorganic CVD (MOCVD), a lift off method, a shadow mask method, and aplating method such as an electrolytic plating method, anon-electrolytic plating method or a combination of the electrolyticplating method and the non-electrolytic plating method, and a patterningtechnique may be combined as necessary. In addition, as the PVD method,(a) various vacuum evaporation methods such as an electron beam heatingmethod, a resistance heating method, a flash evaporation method, and amethod of heating a crucible, (b) a plasma deposition method, (c)various sputtering methods such as a dipole sputtering method, a directcurrent sputtering method, a direct current magnetron sputtering method,a high-frequency sputtering method, a magnetron sputtering method, anion beam sputtering method, and a bias sputtering method, (d) a directcurrent (DC) method, a radio frequency (RF) method, a multi cathodemethod, an activation reaction method, an electric field depositionmethod, and various ion plating methods such as a high frequency ionplating method and a reactive ion plating method may be employed. When aresist pattern is formed, for example, a resist material is coated toform a resist layer, and a photolithography technique, a laserlithography technique, an electron beam lithography technique, or anX-beam lithography technique is then used to pattern the resist layer. Aresist transfer method or the like may be used to form the resistpattern. When the control electrode, the first electrode, the secondelectrode, the gate electrode, or the source/drain electrodes are formedon the basis of an etching method, a dry etching method or a wet etchingmethod may be employed, and ion milling or RIE may be employed as thedry etching method, for example. In addition, the control electrode, thefirst electrode, the second electrode, the gate electrode, or thesource/drain electrodes may be formed on the basis of a laser ablationmethod, a mask deposition method, a laser transfer method, and so forth.

The insulating layer or the gate insulating layer (hereinafter, thesemay be collectively referred to as a gate insulating layer or the like)may be single-layered or multi-layered. As a material for forming thegate insulating layer or the like, not only an inorganic insulatingmaterial illustrated by a silicon oxide based material, a siliconnitride (SiN_(Y)), and a metal oxide high-k insulating film such asaluminum oxide (Al₂O₃) or HfO₂ but also an organic insulating material(organic polymer) illustrated by polymethylmethacrylate (PMMA),polyvinylphenol (PVP), polyvinyl alcohol (PVA), polyimide, polycarbonate(PC), polyethylene terephthalate (PET), polystyrene, N-2(aminoethyl)3-aminopropyl trimethoxysilane (AEAPTMS), 3-mercaptopropyltrimethoxysilane (MPTMS), a silanol derivative such as octadecyltrichlorosilane (OTS) (a silane coupling agent), octadecanethiol, and astraight chain hydrocarbon having a functional group capable of beingcoupled with the control electrode or the gate electrode at one terminalof dodecyl isocyanate may be employed, and a combination thereof mayalso be used. Here, as the silicon oxide based material, a silicon oxide(SiO_(X)), BPSG, PSG, BSG, AsSG, PbSG, silicon oxynitride (SiON), aspin-on-glass (SOG), and a low-k SiO₂ based material (e.g.,polyarylether, cycloperfluorocarbon polymer and benzo cyclobutene,cyclic fluorine resin, polytetrafluoroethylene, arylether fluoride,polyimide fluoride, amorphous carbon, and organic SOG) may be employed.

As a method of forming the gate insulating layer or the like, besidesthe coating methods listed above, a combination of any one of a lift offmethod, a sol-gel method, an electrodeposition method and a shadow maskmethod, and a patterning technique may be employed as necessary.

Alternatively, the gate insulating layer may be formed by performingoxidation or nitridation on the surface of the control electrode or thegate electrode or by forming an oxide film or a nitride film on thesurface of the control electrode or the gate electrode. As the method ofperforming oxidation on the surface of the control electrode or the gateelectrode, although also depending on the material for forming thecontrol electrode or the gate electrode, an oxidation method using O₂plasma and an anodization method may be employed. In addition, as themethod of performing nitridation on the surface of the control electrodeor the gate electrode, although also depending on the material forforming the control electrode or the gate electrode, a nitridationmethod using N₂ plasma may be employed. Alternatively, for example, forthe Au electrode, the surface of the control electrode or the gateelectrode is covered by a dipping method or the like in aself-organizing way with insulating molecules having a functional groupcapable of being chemically coupled with the control electrode or thegate electrode such as straight-chain hydrocarbon of which one terminalis modified with the mercapto group, and it is thus possible to form thegate insulating layer on the surface of the control electrode or thegate electrode. Alternatively, the gate insulating layer may be formedby modifying the surface of the control electrode or the gate electrodewith a silanol derivative (silane coupling agent).

In the present disclosure, the base may include a silicon oxide basedmaterial (e.g., SiO_(x) or SOG), a silicon nitride (SiN_(Y)), and ametal oxide high-k insulating film such as aluminum oxide (Al₂O₃) orHfO₂. When the base is formed of these materials, the base may be formedon a support (or above the support) properly selected from materialslisted below. That is, as the support or a base other than the basedescribed above, a plastic film, a plastic sheet, or a plastic substratehaving flexibility including an organic polymer illustrated bypolymethyl methacrylate (polymethacrylic acid methyl (PMMA)) or PVA,PVP, polyether sulfone (PES), polyimide, PC, PET, polyethylenenaphthalate (PEN), or mica may be employed. For example, when the baseformed of the high-molecular material such as the organic polymer havingflexibility is used, it is possible to assemble an electronic device ora semiconductor device with a display device or electronic equipmenthaving a curved surface shape. Alternatively, as the base, various glasssubstrates, various glass substrates having an insulating film formed ona surface thereof, a quartz substrate, a quartz substrate having aninsulating film formed on a surface thereof, a silicon substrate havingan insulating film formed on a surface thereof, a sapphire substrate, ametallic substrate formed of various alloys such as stainless steel orvarious metals may be employed. For the support having an electricallyinsulating property, any material listed above may be properly selected.Also, as the support, a conductive substrate (a substrate formed of ametal such as gold or aluminum, a substrate formed of high-orientationgraphite, or a stainless steel substrate) may be employed. In addition,depending on the configuration and structure of the semiconductordevice, the semiconductor device may be formed on the support. However,the support may also be formed of the material listed above.

The present disclosure may be applied to an image display device or amethod of manufacturing the image display device, for example. Here, asthe image display device, various image display devices such asso-called desktop-type personal computers, notebook-type personalcomputers, mobile-type personal computers, personal digital assistants(PDAs), cellular phones, gaming machines, electronic books, electronicpapers such as electronic newspapers, signboards, posters, bulletinboards such as black boards, copying machines, rewritable papersreplacing printer papers, electronic calculators, display portions ofhome appliances, card display portions of point cards or the like,electronic advertisements, electronic POPs, and so forth may beemployed. In addition, various illumination devices may also beemployed.

When the electronic device or the semiconductor device of the presentdisclosure is applied to display devices or a variety of electronicequipment and used, it may be used as a monolithic integrated circuit inwhich the support is integrated with a number of semiconductor devices,and may also be used as a discrete part after the electronic devices ofthe semiconductor devices are individually diced. In addition, theelectronic device or the semiconductor device may be sealed with aresin.

First Embodiment

The first embodiment relates to an electronic device according to thefirst to sixth aspects of the present disclosure, and in particular,relates to a bottom gate-bottom contact type TFT having a three-terminalstructure and a method of manufacturing a semiconductor device accordingto the first and second aspects of the present disclosure.

The electronic device of the first embodiment or the second to eighthembodiments includes at least a first electrode, a second electrodedisposed to be spaced apart from the first electrode, and an activelayer disposed over a second electrode from above the first electrodeand formed of an organic semiconductor material, and a charge injectionlayer is disposed between the first electrode and the active layer andbetween the second electrode and the active layer.

Here, in the bottom gate-bottom contact type TFT having thethree-terminal structure of the first embodiment, as shown in FIG. 1Dschematically illustrating a partial cross-sectional view, a gateelectrode 12 is formed on a base 11 as a control electrode, a gateinsulating layer 13 is formed on the gate electrode 12 and the base 11as an insulating layer, a pair of source/drain electrodes 15 are formedon the gate insulating layer 13 as first and second electrodes, achannel formation region 14 formed on the gate insulating layer 13between the pair of source/drain electrodes 15 and a channel formationregion extension 14A formed above the source/drain electrodes 15 areformed as an active layer, and a charge injection layer 16 is formedbetween each of the source/drain electrodes 15 and the channel formationregion extension 14A.

Here, the base 11 is formed of a silicon substrate, the gate electrode12 (control electrode) is formed of gold (Au), the gate insulating layer13 (insulating layer) is formed of SiO₂, the source/drain electrodes 15(first and second electrodes) are formed of gold (Au), and the channelformation region 14 and the channel formation region extension 14A(active layer) are formed of pentacene. This is also applied to thesecond to eighth embodiments to be described later in the same way.

In addition, in the first embodiment, the charge injection layer 16 isformed of an organic material having an increased electric conductivitywhen the charge injection layer is oxidized. In addition, when the valueof the electric conductivity (electrical conductivity, conductivity) ofan organic compound for forming a charge injection layer-precursor layeris denoted with σ₁ and the value of the electric conductivity of theorganic compound for forming the charge injection layer obtained byperforming oxidation on the charge injection layer-precursor layer isdenoted with σ₂, σ₂/σ₁ equals to 0.06 Ω⁻¹·m⁻¹/1×10⁻⁵ Ω⁻¹·m⁻¹=6000.Alternatively, the charge injection layer 16 is formed of an oxide of aWeitz type oxidation-reduction based organic compound(oxidation-reduction based organic compound that generates a six-πsystem at a terminal of a molecular structure in an oxidized state).Alternatively, the charge injection layer 16 is formed of an oxide of anorganic compound having a cyclic structure in which the number of πelectrons is 4n+3 (n is a positive integer). Alternatively, the chargeinjection layer 16 is formed of an oxide of an organic compound having adichalcogen five-membered ring. Alternatively, the charge injectionlayer 16 is formed of an oxide of TTF. This is also applied to thesecond to eighth embodiments to be described later in the same way.Here, the Weitz type oxidation-reduction based organic compound or thecyclic material having 4n+3π electrons generates 6π systems by pullingout one electron (i.e., by performing oxidation), or is easily oxidizedin the air because it forms a stable aromatic ring having 4n+2πelectrons. That is, the compound is disposed in the air, and holes arespontaneously doped, thereby enhancing the electric conductivity. Suchan organic compound is disposed at an interface between the electrodeand the organic semiconductor material, and it is thus possible toeasily introduce a doping layer for charge injection with goodcontrollability. As a result, high performance and high reliabilitydevice by suppressing element degradation due to degradation of acontact portion can be achieved in the electronic device or thesemiconductor.

Hereinafter, a method of manufacturing the semiconductor device of thefirst embodiment will be described with reference to FIGS. 1A to 1Dschematically illustrating partial cross-sectional views of a base orthe like.

[Process-100]

First, the gate electrode 12 is formed on the base 11. In particular, apattern for forming the gate electrode based on a resist layer is formedon the base 11. A Ti layer as an adhesive layer and an Au layer as thegate electrode 12 are then sequentially formed on the base 11 and theresist layer by a vacuum evaporation method. The adhesive layer is notshown in the drawings. When the evaporation is performed, the base 11 iscarried on a base holder (not shown) that can adjust the temperature andsuppress the increase in base temperature during the evaporation, and itis thus possible to perform film formation in which deformation of thebase 11 is suppressed as much as possible. The resist layer is thenremoved by a lift-off method, and it is thus possible to obtain the gateelectrode 12 formed of the Au layer.

[Process-110]

Next, the gate insulating layer 13 is formed on the base 11 and the gateelectrode 12. That is, the gate insulating layer 13 is formed over anentire surface of the obtained structure. In particular, the gateinsulating layer 13 formed of SiO₂ is formed on the gate electrode 12and the base 11 on the basis of a sputtering method (see FIG. 1A). Whenformation of the gate insulating layer 13 is performed, a portion of thegate electrode 12 is covered by a hard mask, and it is thus possible toform an extraction portion of the gate electrode 12 (not shown) withouta photolithography process.

[Process-120]

Next, a pair of source/drain electrodes 15 is formed on the gateinsulating layer 13. In particular, a titanium (Ti) layer (not shown)having a thickness of about 0.5 nm as an adhesive layer and a gold (Au)layer having a thickness of about 25 nm as the source/drain electrodes15 are sequentially formed on the basis of a vacuum evaporation method.When these layers are formed, a portion of the gate insulating layer 13is covered by a hard mask, and it is thus possible to form thesource/drain electrodes 15 without a photolithography process.

[Process-130]

Next, a charge injection layer-precursor layer formed of an organiccompound is formed on each of the source/drain electrodes 15 on thebasis of an inkjet printing method. In addition, as described above, theorganic compound includes the Weitz type oxidation-reduction basedorganic compound, the organic compound having a cyclic structure inwhich the number of π electrons is 4n+3 (n is a positive integer), theorganic compound having the dichalcogen five-membered ring, or anorganic compound having a monochalcogen six-membered ring to bedescribed later. Oxidation is then performed on the charge injectionlayer-precursor layer, thereby obtaining the charge injection layer 16having a thickness of 5 nm (see FIG. 1C). The charge injection layer 16is formed only on top surfaces of the source/drain electrodes 15 in thedrawing. However, the charge injection layer 16 is not formed only onthe top surfaces of the source/drain electrodes 15 but may also beformed on side surfaces of the source/drain electrodes 15. This alsoapplies to the embodiments to be described below in the same way. Theoxidation performed on the charge injection layer-precursor layer isnatural oxidation under an air atmosphere, but is not limited thereto.The oxidation (including heating on the charge injection layer-precursorlayer) may be performed under an oxygen gas atmosphere (or under anoxidation atmosphere). In particular, the oxidation was performed inconditions of air atmosphere, 60° C., and 30 minutes. In this way, TTFis oxidized as shown in FIG. 9.

[Process-140]

Next, a channel formation region 14 formed of an organic semiconductormaterial is formed on the gate insulating layer 13 located between thepair of source/drain electrodes 15, and a channel formation regionextension 14A formed of the organic semiconductor material is alsoformed above each of the source/drain electrodes 15, in particular, onthe charge injection layer 16 (see FIG. 1D). In particular, an organicsemiconductor material layer is formed on an entire surface of theobtained structure on the basis of a spin coating method and then dried.The organic semiconductor material layer is then patterned as necessary,and it is thus possible to obtain the channel formation region 14 andthe channel formation region extension 14A.

For example, in the method of manufacturing an image display device,subsequent to this process, an image display portion (in particular, forexample, an image display portion including an organicelectroluminescence element, an electrophoretic display element, or asemiconductor light emitting element) may be formed on or above thesemiconductor device on the basis of well-known methods. Also, in eachof the embodiments to be described below, the same processes may beperformed after completion of manufacturing of the electronic device orthe semiconductor device, thereby obtaining the image display portion.

In the first embodiment, since the charge injection layer 16 is formed,the value of the contact resistance between the source/drain electrodes15 and the channel formation region extension 14A can be reduced byabout 85% in comparison with a comparative example in which the chargeinjection layer 16 is not formed. In addition, an effective mobility canbe enhanced. FIGS. 10 and 11 illustrate measurement results of contactresistance values and measurement results of the effective mobilities ofthe first embodiment and the comparative example, respectively. Here,the curves A and B in FIGS. 10 and 11 illustrate the measurement resultsof the first embodiment and the comparative example. The horizontal axisof FIG. 10 indicates a channel length (unit: 10⁻³ cm) and the verticalaxis of FIG. 10 indicates the contact resistance (unit: 10⁶ Ω·cm). Thevalue of the y-intercept is a contact resistance value. In addition, thehorizontal axis of FIG. 11 indicates the gate-source voltage V_(GS)(unit: V), and the vertical axis of FIG. 11 indicates the drain currentI_(D) (unit: 10⁻⁶ A). In addition, the drain voltage V_(d) is constantly−30 V.

In addition, the charge injection layer-precursor layer may be formed ofa derivative of TTF (in particular, MDT-TTF having a thickness of 5 nm)instead of TTF and the semiconductor device may be manufactured by thesame method as in the first embodiment, thereby reducing the contactresistance by the same degree as in the first embodiment. Similarly, thecharge injection layer-precursor layer may be formed oftetrathiapentalene, a derivative of tetrathiapentalene (in particular,TTM-TTP, CnTTM-TTP), tetrathiatetracene, or hexathiopentacene and thesemiconductor device may be manufactured by the same method as in thefirst embodiment, thereby also reducing the contact resistance by thesame degree as in the first embodiment.

In addition, the charge injection layer 16 is formed of an oxide of theorganic compound having the monochalcogen six-membered ring. Inparticular, the charge injection layer-precursor layer is formed ofpyranylidene or bithiapyrinylidene and the semiconductor device ismanufactured by the same method as in the first method, thereby alsoreducing the contact resistance by the same degree as in the firstembodiment.

Second Embodiment

The second embodiment relates to the electronic device according to thefirst to sixth aspects of the present disclosure, and in particular,relates to a bottom gate-top contact type TFT having a three-terminalstructure and a method of manufacturing the semiconductor deviceaccording to the third and fourth aspects of the present disclosure.

In the bottom gate-top contact type TFT having the three-terminalstructure of the second embodiment, as shown in FIG. 2D schematicallyillustrating the partial cross-sectional view, a gate electrode 22formed on a base 21 is formed as a control electrode, a gate insulatinglayer 23 is formed on the gate electrode 22 and the base 21 as aninsulating layer, a channel formation region 24 and a channel formationregion extension 24A are formed on the gate insulating layer 23 as anactive layer, a pair of source/drain electrodes 25 are formed above thechannel formation region extension 24A as first and second electrodes,and a charge injection layer 26 is formed between each of thesource/drain electrodes 25 and the channel formation region extension24A.

Hereinafter, a method of manufacturing the semiconductor device of thesecond embodiment will be described with reference to FIGS. 2A to 2Dillustrating partial cross-sectional views of the base or the like.

[Process-200]

First, the gate electrode 22 is formed on the base 21 in the same way asin [Process-100] of the first embodiment and then the gate insulatinglayer 23 is formed on the base 21 and the gate electrode 22 in the sameway as in [Process-110] of the first embodiment (see FIG. 2A).

[Process-210]

Next, the channel formation region 24 and the channel formation regionextension 24A formed of an organic semiconductor material are formed onthe gate insulating layer 23 in the same way as in [Process-140] of thefirst embodiment (see FIG. 2B). In addition, although the organicsemiconductor material layer may be patterned to obtain the channelformation region 24 and the channel formation region extension 24A asnecessary, pattering the organic semiconductor material layer may beperformed after [Process-220] to be described later or may also beperformed after [Process-230].

[Process-220]

Next, in the same way as in [Process-130] of the first embodiment, thecharge injection layer-precursor layer formed of an organic compound isformed on the channel formation region extension 24A, and then oxidationis performed on the charge injection layer-precursor layer. In this way,the charge injection layer 26 having a higher electric conductivity thanthe charge injection layer-precursor layer can be formed (see FIG. 2C).In addition, as described above, the organic compound includes at leastone selected from the group including the Weitz type oxidation-reductionbased organic compound, the organic compound having the cyclic structurein which the number of π electrons is 4n+3 (n is a positive integer),the organic compound having the dichalcogen five-membered ring, and theorganic compound having the monochalcogen six-membered ring.

[Process-230]

Next, in the same way as in [Process-120] of the first embodiment, thepair of source/drain electrodes 25 are formed above the channelformation region extension 24A, in particular, on the charge injectionlayer 26 (see FIG. 2D).

In the second embodiment, with the formation of the charge injectionlayer 26, the value of the contact resistance between the source/drainelectrodes 25 and the channel formation region extension 24A can also bedecreased by the same degree as in the first embodiment in comparisonwith the comparative example in which the charge injection layer 26 isnot formed.

In addition, the charge injection layer-precursor layer may be formed ofa derivative of TTF instead of TTF (in particular, the derivative of TTFdescribed in the first embodiment), and the semiconductor device may bemanufactured by the same method as in the second embodiment, therebyreducing the contact resistance by the same degree as in the secondembodiment. Similarly, the charge injection layer-precursor layer may beformed of tetrathiapentalene, a derivative of tetrathiapentalene (inparticular, the derivative of tetrathiapentalene described in the firstembodiment), tetrathiatetracene, or hexathiopentacene, and thesemiconductor device may be manufactured by the similar method as in thesecond embodiment, thereby also reducing the contact resistance by thesame degree as in the second embodiment.

In addition, the charge injection layer may be configured of an oxide ofan organic compound having a monochalcogen six-membered ring, inparticular, the charge injection layer-precursor layer may be configuredof pyranylidene, a derivative of pyranylidene (in particular, thederivative of pyranylidene described in the first embodiment),bithiapyrinylidene, a derivative of bithiapyrinylidene (in particular,the derivative of bithiapyrinylidene described in the first embodiment)and the semiconductor device may be manufactured by the same method asin the second embodiment, thereby also reducing the contact resistanceby the same degree as in the second embodiment.

Third Embodiment

The third embodiment is a modified example of the method ofmanufacturing the semiconductor device described in the secondembodiment.

Hereinafter, a method of manufacturing the semiconductor device of thethird embodiment will be described with reference to FIGS. 3A to 3Dschematically illustrating partial cross-sectional views of the base orthe like.

[Process-300]

First, the gate electrode 22 is formed on the base 21 in the same way asin [Process-100] of the first embodiment, and then the gate insulatinglayer 23 is formed on the base 21 and the gate electrode 22 in the sameway as in [Process-110] of the first embodiment.

[Process-310]

Next, in the same way as in [Process-140] of the first embodiment, anorganic semiconductor material layer 24B formed of an organicsemiconductor material is formed on the gate insulating layer 23, andthen a charge injection layer-precursor layer formed of an organiccompound is formed on the organic semiconductor material layer 24B onthe basis of a spin coating method. The charge injection layer-precursorlayer is then oxidized. It is thus possible to form the charge injectionlayer 26 having a higher electric conductivity than the charge injectionlayer-precursor layer (see FIG. 3A). The charge injection layer 26 andthe organic semiconductor material layer 24B are then patterned, therebyobtaining the structure having the channel formation region 24, thechannel formation region extension 24A, and the charge injection layer26 formed on the channel formation region 24 and the channel formationregion extension 24A (see FIG. 3B).

[Process-320]

Next, in the same way as in [Process-120] of the first embodiment, thepair of source/drain electrodes 25 is formed above the channel formationregion extension 24A, in particular, on the charge injection layer 26(see FIG. 3C). In addition, the source/drain electrodes 25 are alsoformed on side surfaces of the channel formation region extension 24Aand the charge injection layer 26 in some cases.

[Process-330]

Next, a portion of the charge injection layer 26 on the channelformation region 24 is removed by etching using the source/drainelectrodes 25 as an etching mask (see FIG. 3D). As for the etching, forexample, a wet etching method using a poor solvent such as ethanol or adry etching method for the organic semiconductor material may beemployed. This also applies to the fourth embodiment or the seventhembodiment in the same way.

Fourth Embodiment

The fourth embodiment is also a modified example of the secondembodiment.

Hereinafter, a method of manufacturing the semiconductor device of thefourth embodiment will be described with reference to FIGS. 4A to 4Dschematically illustrating partial cross-sectional views of the base orthe like.

[Process-400]

First, the gate electrode 22 is formed on the base 21 in the same way asin [Process-100] of the first embodiment, and then the gate insulatinglayer 23 is formed on the base 21 and the gate electrode 22 in the sameway as in [Process-110] of the first embodiment.

[Process-410]

Next, in the similar way as in [Process-140] of the first embodiment,the organic semiconductor material layer 24B formed of the organicsemiconductor material is formed on the gate insulating layer 23, aphotosensitive fluorine-based insulating material layer is then formedon the organic semiconductor material layer 24B located at a portion ofthe region at which the channel formation region is to be formed, and issubjected to exposure and development, thereby obtaining a protectivelayer 27.

[Process-420]

Next, a charge injection layer-precursor layer formed of the organiccompound is formed on the organic semiconductor material layer 24B andthe protective layer 27 on the basis of a spin coating method. Thecharge injection layer-precursor layer is then oxidized. It is thuspossible to form the charge injection layer 26 having a higher electricconductivity than the charge injection layer-precursor layer (see FIG.4A). The charge injection layer 26 and the organic semiconductormaterial layer 24B are then patterned, thereby obtaining the structurehaving the channel formation region 24, the channel formation regionextension 24A, and the charge injection layer 26 formed on theprotective layer 27 and the channel formation region extension 24A (seeFIG. 4B).

[Process-430]

Next, in the similar way as in [Process-120] of the first embodiment,the pair of source/drain electrodes 25 are formed above the channelformation region extension 24A, in particular, on the charge injectionlayer 26 (see FIG. 4C). In addition, the source/drain electrodes 25 arealso formed on side surfaces of the channel formation region extension24A and the charge injection layer 26 in some cases.

[Process-440]

Next, using the source/drain electrodes 25 as an etching mask, a portionof the charge injection layer 26 on the channel formation region 24 isremoved, for example, by a dry etching method using an oxygen gas (seeFIG. 4D). When the portion of the charge injection layer 26 is removedby etching, the channel formation region is protected by the protectivelayer, 27, and it is thus possible to reliably prevent the channelformation region 24 from being damaged.

Fifth Embodiment

The fifth embodiment relates to an electronic device according to thefirst to sixth aspects of the present disclosure, in particular, relatesto a top gate-bottom contact type TFT having the three-terminalstructure and a method of manufacturing the semiconductor deviceaccording to the fifth and sixth aspects of the present disclosure.

In the top gate-bottom contact type TFT having the three-terminalstructure of the fifth embodiment, as shown in FIG. 5D schematicallyillustrating the partial cross-sectional view, a pair of source/drainelectrodes 35 are formed on a base 31 as first and second electrodes, achannel formation region 34 formed on the base 31 between the pair ofsource/drain electrodes 35 and a channel formation region extension 34Aformed above the source/drain electrodes 35 are formed as an activelayer, a gate insulating layer 33 is formed on the channel formationregion 34 and the channel formation region extension 34A as aninsulating layer, a gate electrode 32 is formed on the gate insulatinglayer 33 to face the channel formation region 34 as a control electrode,and a charge injection layer 36 is formed between the source/drainelectrodes 35 and the channel formation region extension 34A.

Hereinafter, the method of manufacturing the semiconductor device of thefifth embodiment will be described with reference to FIGS. 5A to 5Dschematically illustrating partial cross-sectional views of the base orthe like.

[Process-500]

First, in the same way as in [Process-120] of the first embodiment, thepair of source/drain electrodes 35 are formed on the base 31 (see FIG.5A).

[Process-510]

Next, in the same way as in [Process-130] of the first embodiment, acharge injection layer-precursor layer formed of an organic compound isformed on each of the source/drain electrodes 35, and then the chargeinjection layer-precursor layer is oxidized. It is thus possible to formthe charge injection layer 36 having a higher electric conductivity thanthe charge injection layer-precursor layer (see FIG. 5B). In addition,as described above, the organic compound includes at least one organiccompound selected from the group including the Weitz typeoxidation-reduction based organic compound, the organic compound havingthe cyclic structure in which the number of π electrons is 4n+3 (n is apositive integer), the organic compound having the dichalcogenfive-membered ring, and the organic compound having the monochalcogensix-membered ring.

[Process-520]

Next, in the same way as in [Process-140] of the first embodiment, thechannel formation region 34 formed of the organic semiconductor materialis formed between the pair of source/drain electrodes 35, and thechannel formation region extension 34A formed of the organicsemiconductor material is also formed above each of the source/drainelectrodes 35, in particular, on the charge injection layer 36 (see FIG.5C).

[Process-530]

Next, the gate insulating layer 33 is formed on the channel formationregion 34 and the channel formation region extension 34A in the same wayas in [Process-110] of the first embodiment, and then the gate electrode32 is formed on a portion of the gate insulating layer 33 on the channelformation region 34 in the same way as in [Process-100] of the firstembodiment (see FIG. 5D).

In the fifth embodiment, with the formation of the charge injectionlayer 36, the value of the contact resistance between the source/drainelectrodes 35 and the channel formation region extension 34A can also bedecreased by the same degree as in the first embodiment in comparisonwith the comparative example in which the charge injection layer 36 isnot formed.

In addition, the charge injection layer-precursor layer may be formed ofa derivative of TTF instead of TTF (in particular, the derivative of TTFdescribed in the first embodiment), and the semiconductor device may bemanufactured by the same method as in the fifth embodiment, therebyreducing the contact resistance by the same degree as in the fifthembodiment. Similarly, the charge injection layer-precursor layer may beformed of tetrathiapentalene, a derivative of tetrathiapentalene (inparticular, the derivative of tetrathiapentalene described in the firstembodiment), tetrathiatetracene, or hexathiopentacene, and thesemiconductor device may be manufactured by the same method as in thefifth embodiment, thereby also reducing the contact resistance by thesame degree as in the fifth embodiment.

In addition, the charge injection layer may be configured of an oxide ofan organic compound having a monochalcogen six-membered ring, inparticular, the charge injection layer-precursor layer may be configuredof pyranylidene, a derivative of pyranylidene (in particular, thederivative of pyranylidene described in the first embodiment),bithiapyrinylidene, or a derivative of bithiapyrinylidene (inparticular, the derivative of bithiapyrinylidene described in the firstembodiment), and the semiconductor device may be manufactured by thesame method as in the fifth embodiment, thereby also reducing thecontact resistance by the same degree as in the fifth embodiment.

Sixth Embodiment

The sixth embodiment relates to an electronic device according to thefirst to sixth aspects of the present disclosure, in particular, relatesto the top gate-top contact type TFT having the three-terminal structureand the method of manufacturing the semiconductor device according tothe seventh and eighth aspects of the present disclosure.

In the top gate-top contact type TFT having the three-terminal structureof the sixth embodiment, as shown in FIG. 6D schematically illustratingthe partial cross-sectional view, a channel formation region 44 and achannel formation region extension 44A are formed on a base 41 as anactive layer, a pair of source/drain electrodes 45 are formed above thechannel formation region extension 44A as first and second electrodes, agate insulating layer 43 is formed on the pair of source/drainelectrodes 45 and the channel formation region 44 as an insulatinglayer, a gate electrode 42 is formed on the gate insulating layer 43 asa control electrode, and a charge injection layer 46 is formed betweenthe source/drain electrodes 45 and the channel formation regionextension 44A.

Hereinafter, the method of manufacturing the semiconductor device of thesixth embodiment will be described with reference to FIGS. 6A to 6Dschematically illustrating the partial cross-sectional views of the baseor the like.

[Process-600]

First, the channel formation region 44 and the channel formation regionextension 44A formed of an organic semiconductor material are formed onthe base 41 in the same way as in [Process-140] of the first embodiment(see FIG. 6A).

[Process-610]

Next, in the same way as in [Process-130] of the first embodiment, acharge injection layer-precursor layer formed of an organic compound isformed on the channel formation region extension 44A, and then thecharge injection layer-precursor layer is oxidized. It is thus possibleto form the charge injection layer 46 having a higher electricconductivity than the charge injection layer-precursor layer (see FIG.6B). In addition, as described above, the organic compound includes atleast one organic compound selected from the group including the Weitztype oxidation-reduction based organic compound, the organic compoundhaving the cyclic structure in which the number of π electrons is 4n+3(n is a positive integer), the organic compound having the dichalcogenfive-membered ring, and the organic compound having the monochalcogensix-membered ring.

[Process-620]

Next, the pair of source/drain electrodes 45 are formed above thechannel formation region extension 44A, in particular, on the chargeinjection layer 46 in the same way as in [Process-120] of the firstembodiment (see FIG. 6C).

[Process-630]

Next, the gate insulating layer 43 is formed on the channel formationregion 44 and the pair of source/drain electrodes 45 in the same way asin [Process-110] of the first embodiment, and then the gate electrode 42is formed on a portion of the gate insulating layer on the channelformation region 44 in the same way as in [Process-100] of the firstembodiment (see FIG. 6D).

In the sixth embodiment, with the formation of the charge injectionlayer 46, the value of the contact resistance between the source/drainelectrodes 45 and the channel formation region extension 44A can also bedecreased by the same degree as in the first embodiment in comparisonwith the comparative example in which the charge injection layer 46 isnot formed.

In addition, the charge injection layer-precursor layer may be formed ofa derivative of TTF instead of TTF (in particular, the derivative of TTFdescribed in the first embodiment), and the semiconductor device may bemanufactured by the same method as in the sixth embodiment, therebyreducing the contact resistance by the same degree as in the sixthembodiment. Similarly, the charge injection layer-precursor layer may beformed of tetrathiapentalene, a derivative of tetrathiapentalene (inparticular, the derivative of tetrathiapentalene described in the firstembodiment), tetrathiatetracene, or hexathiopentacene, and thesemiconductor device may be manufactured by the same method as in thesixth embodiment, thereby also reducing the contact resistance by thesame degree as in the sixth embodiment.

In addition, the charge injection layer may be formed of an oxide of anorganic compound having a monochalcogen six-membered ring, inparticular, the charge injection layer-precursor layer may be formed ofpyranylidene, a derivative of pyranylidene (in particular, thederivative of pyranylidene described in the first embodiment),bithiapyrinylidene, or a derivative of bithiapyrinylidene (inparticular, the derivative of bithiapyrinylidene described in the firstembodiment), and the semiconductor device may be manufactured by thesame method as in the sixth embodiment, thereby also reducing thecontact resistance by the same degree as in the sixth embodiment.

Seventh Embodiment

The seventh embodiment is a modified example of the method ofmanufacturing the semiconductor device described in the sixthembodiment.

Hereinafter, the method of manufacturing the semiconductor device of theseventh embodiment will be described with reference to FIGS. 7A to 7Cschematically illustrating the partial cross-sectional views of the baseor the like.

[Process-700]

First, an organic semiconductor material layer formed of an organicsemiconductor material is formed on the base 41 in the same way as in[Process-140] of the first embodiment.

[Process-710]

Next, a charge injection layer-precursor layer formed of an organiccompound is formed on the organic semiconductor material layer on thebasis of a spin coating method. The charge injection layer-precursorlayer is then oxidized. It is thus possible to form the charge injectionlayer 46 having a higher electric conductivity than the charge injectionlayer-precursor layer. The charge injection layer 46 and the organicsemiconductor material layer are then patterned, thereby obtaining thestructure having the channel formation region 44, the channel formationregion extension 44A, and the charge injection layer 46 formed onchannel formation region 44 and the channel formation region extension44A (see FIG. 7A).

[Process-720]

Next, in the same way as in [Process-120] of the first embodiment, thepair of source/drain electrodes 45 are formed above the channelformation region extension 44A, in particular, on the charge injectionlayer 46 (see FIG. 7B). In addition, the source/drain electrodes 45 arealso formed on side surfaces of the channel formation region extension44A and the charge injection layer 46 in some cases.

[Process-730]

Next, a portion of the charge injection layer 46 on the channelformation region 44 is removed by etching using the source/drainelectrodes 45 as an etching mask (see FIG. 7C).

[Process-740]

Next, the gate insulating layer 43 is formed on the channel formationregion 44 and the pair of source/drain electrodes 45 in the same way asin [Process-110] of the first embodiment, and then the gate electrode 42is formed on a portion of the gate insulating layer 43 on the channelformation region 44 in the same way as in [Process-100] of the firstembodiment. It is thus possible to obtain the semiconductor devicehaving the similar configuration and structure to that shown in FIG. 6D.

Eighth Embodiment

The eighth embodiment is a modified example of the fifth or sixthembodiment. However, in the eighth embodiment, in particular, theelectronic device is a two-terminal type electronic device. Further, asshown in FIGS. 8A and 8B schematically illustrating partialcross-sectional views, the electronic device includes a first electrode51, a second electrode, and an active layer 53 formed between the firstelectrode 51 and the second electrode 52. In addition, the active layer53 is formed of an organic semiconductor material. Electric power isgenerated by irradiating light onto the active layer 53. That is, theelectronic device of the eighth embodiment acts as a photoelectricconversion element or a solar cell. Alternatively, the electronic deviceacts as a light emitting element of which the active layer 53 emitslight when a voltage is applied to the first electrode 51 and the secondelectrode 52. Here, a charge injection layer 54 is formed between thefirst electrode 51 and an active layer extension 53A and between thesecond electrode 52 and the active layer extension 53A. In addition, thereference numeral 50 indicates the base.

Except for the description above and that the control electrode and theinsulating layer are not formed, the configuration and structure of theelectronic device of the eighth embodiment can be fundamentally same asthe configuration and structure of the electronic device described inthe fifth or sixth embodiment, and the detailed description is thusomitted. The electronic device of the eighth embodiment may be obtainedby performing the same processes as [Process-500] to [Process-520] ofthe fifth embodiment or the same processes as [Process-600] to[Process-620] of the sixth embodiment. In addition, the structure andconfiguration in which the first electrode, the charge injection layer,the active layer, the charge injection layer, and the second electrodeare sequentially stacked on the base may be obtained in some cases.

Preferred embodiments of the present disclosure have been described, butthe present disclosure is not limited to these embodiments. Thestructure or configuration, formation conditions, and manufacturingconditions of the electronic device or the semiconductor device aremerely illustrative and may be modified as appropriate. For example,when the electronic device (semiconductor device) obtained in thepresent disclosure is applied to display devices or a variety ofelectronic equipment and used, it may be used as a monolithic integratedcircuit of which the base or support is integrated with a number ofelectronic devices (semiconductor devices), and may also be used as adiscrete part after the electronic devices (semiconductor devices) areindividually diced.

Additionally, the present technology may also be configured as below.

[1]<<Electronic Device: First Aspect>>

An electronic device comprising at least:

a first electrode;

a second electrode disposed to be spaced apart from the first electrode;and

an active layer disposed over the second electrode from above the firstelectrode and formed of an organic semiconductor material,

wherein a charge injection layer is formed between the first electrodeand the active layer and between the second electrode and the activelayer, and

the charge injection layer is formed of an organic material having anincreased electric conductivity when the charge injection layer isoxidized.

[2]<<Electronic Device: Second Aspect>>

An electronic device comprising at least:

a first electrode;

a second electrode disposed to be spaced apart from the first electrode;and

an active layer disposed over the second electrode from above the firstelectrode and formed of an organic semiconductor material,

wherein a charge injection layer is formed between the first electrodeand the active layer and between the second electrode and the activelayer, and

the charge injection layer is formed of an oxide of a Weitz typeoxidation-reduction based organic compound.

[3]<<Electronic Device: Third Aspect>>

An electronic device comprising at least:

a first electrode;

a second electrode disposed to be spaced apart from the first electrode;and

an active layer disposed over the second electrode from above the firstelectrode and formed of an organic semiconductor material,

wherein a charge injection layer is formed between the first electrodeand the active layer and between the second electrode and the activelayer, and

the charge injection layer is formed of an oxide of an organic compoundhaving a cyclic structure in which the number of π electrons is 4n+3 (nis a positive integer).

[4]<<Electronic Device: Fourth Aspect>>

An electronic device comprising at least:

a first electrode;

a second electrode disposed to be spaced apart from the first electrode;and

an active layer disposed over the second electrode from above the firstelectrode and formed of an organic semiconductor material,

wherein a charge injection layer is formed between the first electrodeand the active layer and between the second electrode and the activelayer, and

the charge injection layer is formed of an oxide of an organic compoundincluding a dichalcogen five-membered ring.

[5]<<Electronic Device: Fifth Aspect>>

An electronic device comprising at least:

a first electrode;

a second electrode disposed to be spaced apart from the first electrode;and an active layer disposed over the second electrode from above thefirst electrode and formed of an organic semiconductor material,

wherein a charge injection layer is formed between the first electrodeand the active layer and between the second electrode and the activelayer, and the charge injection layer is formed of an oxide of anorganic compound including a monochalcogen six-membered ring.

[6]<<Electronic Device: Sixth Aspect>>

An electronic device comprising at least:

a first electrode;

a second electrode disposed to be spaced apart from the first electrode;and

an active layer disposed over the second electrode from above the firstelectrode and formed of an organic semiconductor material,

wherein a charge injection layer is formed between the first electrodeand the active layer and between the second electrode and the activelayer, and

the charge injection layer is formed of an oxide of at least one organiccompound selected from the group including tetrathiafulvalene and aderivative thereof, tetrathiapentalene and a derivative thereof,tetrathiatetracene, hexathiopentacene, pyranylidene and a derivativethereof, and bithiapyrinylidene and a derivative thereof.

[7] The electronic device according to any one of [1] to [6], furthercomprising:

an insulating layer; and

a control electrode disposed to face a portion of the active layerlocated between the first electrode and the second electrode with theinsulating layer interposed therebetween.

[8]<<Bottom Gate-Bottom Contact Type>>

The electronic device according to claim 7, wherein

a gate electrode is formed on the base as the control electrode,

a gate insulating layer is formed on the gate electrode and the base asthe insulating layer,

a pair of source/drain electrodes are formed on the gate insulatinglayer as the first and second electrodes,

as the active layer, a channel formation region is formed on the gateinsulating layer between the pair of source/drain electrodes and achannel formation region extension is also formed above the source/drainelectrodes, and

a charge injection layer is formed between the source/drain electrodesand the channel formation region extension.

[9]<<Bottom Gate-Top Contact Type>>

The electronic device according to [7], wherein

a gate electrode is formed on the base as the control electrode,

a gate insulating layer is formed on the gate electrode and the base asthe insulating layer,

a channel formation region and a channel formation region extension areformed on the gate insulating layer as the active layer,

a pair of source/drain electrodes are formed above the channel formationregion extension as the first and second electrodes, and

a charge injection layer is formed between each of the source/drainelectrodes and the channel formation region extension.

[10]<<Top Gate-Bottom Contact Type>>

The electronic device according to [7], wherein

a pair of source/drain electrodes are formed on the base as the firstand second electrodes,

as the active layer, a channel formation region is formed on the basebetween the pair of source/drain electrodes and a channel formationregion extension is also formed above the source/drain electrodes,

a gate insulating layer is formed on the channel formation region andthe channel formation region extension as the insulating layer,

a gate electrode is formed on the gate insulating layer to face thechannel formation region as the control electrode, and

the charge injection layer is formed between each of the source/drainelectrodes and the channel formation region extension.

[11]<<Top Gate-Top Contact Type>>

The electronic device according to [7], wherein

a channel formation region and a channel formation region extension areformed on the base as the active layer,

a pair of source/drain electrodes are formed above the channel formationregion extension as the first and second electrodes,

a gate insulating layer is formed on the pair of source/drain electrodesand the channel formation region as the insulating layer,

a gate electrode is formed on the gate insulating layer as the controlelectrode, and

the charge injection layer is formed between each of the source/drainelectrodes and the channel formation region extension.

[12]<<Method of Manufacturing Semiconductor Device: First Aspect: BottomGate-Bottom Contact Type>>

A method of manufacturing a semiconductor device, comprising

(A) forming a gate electrode on a base, and then forming a gateinsulating layer on the base and the gate electrode;

(B) forming a pair of source/drain electrodes on the gate insulatinglayer; and

(C) forming a channel formation region formed of an organicsemiconductor material on the gate insulating layer disposed between thepair of source/drain electrodes and additionally forming a channelformation region extension formed of the organic semiconductor materialabove each of the source/drain electrodes,

the method further comprising:

between processes (B) and (C), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer havinga higher electric conductivity than the charge injection layer-precursorlayer.

[13]<<Method of Manufacturing Semiconductor Device: Second Aspect:Bottom Gate-Bottom Contact Type>>

A method of manufacturing a semiconductor device, comprising:

(A) forming a gate electrode on a base, and then forming a gateinsulating layer on the base and the gate electrode;

(B) forming a pair of source/drain electrodes on the gate insulatinglayer; and

(C) forming a channel formation region formed of an organicsemiconductor material on the gate insulating layer disposed between thepair of source/drain electrodes and additionally forming a channelformation region extension formed of the organic semiconductor materialabove each of the source/drain electrodes,

the method further comprising:

between processes (B) and (C), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer,

wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring.

[14]<<Method of Manufacturing Semiconductor Device: Third Aspect: BottomGate-Top Contact Type>>

A method of manufacturing a semiconductor device, comprising:

(A) forming a gate electrode on a base, and then forming a gateinsulating layer on the base and the gate electrode;

(B) forming a channel formation region and a channel formation regionextension formed of an organic semiconductor material on the gateinsulating layer; and

(C) forming a pair of source/drain electrodes above the channelformation region extension,

the method further comprising:

between processes (B) and (C), forming a charge injectionlayer-precursor layer formed of an organic compound on the channelformation region extension, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer havinga higher electric conductivity than the charge injection layer-precursorlayer.

[15]<<Method of Manufacturing Semiconductor Device: Fourth Aspect:Bottom Gate-Top Contact Type>>

A method of manufacturing a semiconductor device, comprising:

(A) forming a gate electrode on a base, and then forming a gateinsulating layer on the base and the gate electrode;

(B) forming a channel formation region and a channel formation regionextension formed of an organic semiconductor material on the gateinsulating layer; and (C) forming a pair of source/drain electrodesabove the channel formation region extension,

the method further comprising:

between processes (B) and (C), forming a charge injectionlayer-precursor layer formed of an organic compound on the channelformation region extension, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer,

wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring.

[16]<<Method of Manufacturing Semiconductor Device: Fifth Aspect: TopGate-Bottom Contact Type>>

A method of manufacturing a semiconductor device, comprising:

(A) forming a pair of source/drain electrodes on a base;

(B) forming a channel formation region formed of an organicsemiconductor material between the pair of source/drain electrodes andadditionally forming a channel formation region extension formed of theorganic semiconductor material above each of the source/drainelectrodes; and

(C) forming a gate insulating layer on the channel formation region andthe channel formation region extension, and then forming a gateelectrode on a portion of the gate insulating layer on the channelformation region,

the method further comprising:

between processes (A) and (B), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer havinga higher electric conductivity than the charge injection layer-precursorlayer.

[17]<<Method of Manufacturing Semiconductor Device: Sixth Aspect: TopGate-Bottom Contact Type>>

A method of manufacturing a semiconductor device, comprising:

(A) forming a pair of source/drain electrodes on a base;

(B) forming a channel formation region formed of an organicsemiconductor material between the pair of source/drain electrodes andadditionally forming a channel formation region extension formed of theorganic semiconductor material above each of the source/drainelectrodes; and

(C) forming a gate insulating layer on the channel formation region andthe channel formation region extension, and then forming a gateelectrode on a portion of the gate insulating layer on the channelformation region,

the method further comprising:

between processes (A) and (B), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer,

wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring.

[18]<<Method of Manufacturing Semiconductor Device: Seventh Aspect: TopGate-Top Contact Type>>

A method of manufacturing a semiconductor device, comprising:

(A) forming a channel formation region and a channel formation regionextension formed of an organic semiconductor material on a base;

(B) forming a pair of source/drain electrodes above the channelformation region extension; and

(C) forming a gate insulating layer on the channel formation region andthe pair of source/drain electrodes, and then forming a gate electrodeon a portion of the gate insulating layer on the channel formationregion,

the method further comprising:

between processes (A) and (B), forming a charge injectionlayer-precursor layer formed of an organic compound on the channelformation region extension, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer havinga higher electric conductivity than the charge injection layer-precursorlayer.

[19]<<Method of Manufacturing Semiconductor Device: Eighth Aspect: TopGate-Top Contact Type>>

A method of manufacturing a semiconductor device, comprising:

(A) forming a channel formation region and a channel formation regionextension formed of an organic semiconductor material on a base;

(B) forming a pair of source/drain electrodes above the channelformation region extension; and

(C) forming a gate insulating layer on the channel formation region andthe pair of source/drain electrodes, and then forming a gate electrodeon a portion of the gate insulating layer on the channel formationregion,

the method further comprising:

between processes (A) and (B), forming a charge injectionlayer-precursor layer formed of an organic compound on the channelformation region extension, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer,

wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring.

[20] The method according to any one of [12] to [19], wherein theoxidation performed on the charge injection layer-precursor layer isnatural oxidation under an air atmosphere.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-148018 filed in theJapan Patent Office on Jul. 4, 2011, the entire content of which ishereby incorporated by reference.

1. An electronic device comprising at least: a first electrode; a secondelectrode disposed to be spaced apart from the first electrode; and anactive layer disposed over the second electrode from above the firstelectrode and formed of an organic semiconductor material, wherein acharge injection layer is formed between the first electrode and theactive layer and between the second electrode and the active layer, andthe charge injection layer is formed of an organic material having anincreased electric conductivity when the charge injection layer isoxidized.
 2. An electronic device comprising at least: a firstelectrode; a second electrode disposed to be spaced apart from the firstelectrode; and an active layer disposed over the second electrode fromabove the first electrode and formed of an organic semiconductormaterial, wherein a charge injection layer is formed between the firstelectrode and the active layer and between the second electrode and theactive layer, and the charge injection layer is formed of an oxide of aWeitz type oxidation-reduction based organic compound.
 3. An electronicdevice comprising at least: a first electrode; a second electrodedisposed to be spaced apart from the first electrode; and an activelayer disposed over the second electrode from above the first electrodeand formed of an organic semiconductor material, wherein a chargeinjection layer is formed between the first electrode and the activelayer and between the second electrode and the active layer, and thecharge injection layer is formed of an oxide of an organic compoundhaving a cyclic structure in which the number of π electrons is 4n+3 (nis a positive integer).
 4. An electronic device comprising at least: afirst electrode; a second electrode disposed to be spaced apart from thefirst electrode; and an active layer disposed over the second electrodefrom above the first electrode and formed of an organic semiconductormaterial, wherein a charge injection layer is formed between the firstelectrode and the active layer and between the second electrode and theactive layer, and the charge injection layer is formed of an oxide of anorganic compound including a dichalcogen five-membered ring.
 5. Anelectronic device comprising at least: a first electrode; a secondelectrode disposed to be spaced apart from the first electrode; and anactive layer disposed over the second electrode from above the firstelectrode and formed of an organic semiconductor material, wherein acharge injection layer is formed between the first electrode and theactive layer and between the second electrode and the active layer, andthe charge injection layer is formed of an oxide of an organic compoundincluding a monochalcogen six-membered ring.
 6. An electronic devicecomprising at least: a first electrode; a second electrode disposed tobe spaced apart from the first electrode; and an active layer disposedover the second electrode from above the first electrode and formed ofan organic semiconductor material, wherein a charge injection layer isformed between the first electrode and the active layer and between thesecond electrode and the active layer, and the charge injection layer isformed of an oxide of at least one organic compound selected from thegroup including tetrathiafulvalene and a derivative thereof,tetrathiapentalene and a derivative thereof, tetrathiatetracene,hexathiopentacene, pyranylidene and a derivative thereof, andbithiapyrinylidene and a derivative thereof.
 7. The electronic deviceaccording to claim 1, further comprising: an insulating layer; and acontrol electrode disposed to face a portion of the active layer locatedbetween the first electrode and the second electrode with the insulatinglayer interposed therebetween.
 8. The electronic device according toclaim 7, wherein a gate electrode is formed on the base as the controlelectrode, a gate insulating layer is formed on the gate electrode andthe base as the insulating layer, a pair of source/drain electrodes areformed on the gate insulating layer as the first and second electrodes,as the active layer, a channel formation region is formed on the gateinsulating layer between the pair of source/drain electrodes and achannel formation region extension is also formed above the source/drainelectrodes, and a charge injection layer is formed between thesource/drain electrodes and the channel formation region extension. 9.The electronic device according to claim 7, wherein a gate electrode isformed on the base as the control electrode, a gate insulating layer isformed on the gate electrode and the base as the insulating layer, achannel formation region and a channel formation region extension areformed on the gate insulating layer as the active layer, a pair ofsource/drain electrodes are formed above the channel formation regionextension as the first and second electrodes, and a charge injectionlayer is formed between each of the source/drain electrodes and thechannel formation region extension.
 10. The electronic device accordingto claim 7, wherein a pair of source/drain electrodes are formed on thebase as the first and second electrodes, as the active layer, a channelformation region is formed on the base between the pair of source/drainelectrodes and a channel formation region extension is also formed abovethe source/drain electrodes, a gate insulating layer is formed on thechannel formation region and the channel formation region extension asthe insulating layer, a gate electrode is formed on the gate insulatinglayer to face the channel formation region as the control electrode, andthe charge injection layer is formed between each of the source/drainelectrodes and the channel formation region extension.
 11. Theelectronic device according to claim 7, wherein a channel formationregion and a channel formation region extension are formed on the baseas the active layer, a pair of source/drain electrodes are formed abovethe channel formation region extension as the first and secondelectrodes, a gate insulating layer is formed on the pair ofsource/drain electrodes and the channel formation region as theinsulating layer, a gate electrode is formed on the gate insulatinglayer as the control electrode, and the charge injection layer is formedbetween each of the source/drain electrodes and the channel formationregion extension.
 12. A method of manufacturing a semiconductor device,comprising (A) forming a gate electrode on a base, and then forming agate insulating layer on the base and the gate electrode; (B) forming apair of source/drain electrodes on the gate insulating layer; and (C)forming a channel formation region formed of an organic semiconductormaterial on the gate insulating layer disposed between the pair ofsource/drain electrodes and additionally forming a channel formationregion extension formed of the organic semiconductor material above eachof the source/drain electrodes, the method further comprising: betweenprocesses (B) and (C), forming a charge injection layer-precursor layerformed of an organic compound on each of the source/drain electrodes,and then performing oxidation on the charge injection layer-precursorlayer to form a charge injection layer having a higher electricconductivity than the charge injection layer-precursor layer.
 13. Amethod of manufacturing a semiconductor device, comprising: (A) forminga gate electrode on a base, and then forming a gate insulating layer onthe base and the gate electrode; (B) forming a pair of source/drainelectrodes on the gate insulating layer; and (C) forming a channelformation region formed of an organic semiconductor material on the gateinsulating layer disposed between the pair of source/drain electrodesand additionally forming a channel formation region extension formed ofthe organic semiconductor material above each of the source/drainelectrodes, the method further comprising: between processes (B) and(C), forming a charge injection layer-precursor layer formed of anorganic compound on each of the source/drain electrodes, and thenperforming oxidation on the charge injection layer-precursor layer toform a charge injection layer, wherein the organic compound includes atleast one organic compound selected from the group including a Weitztype oxidation-reduction based organic compound, an organic compoundhaving a cyclic structure in which the number of π electrons is 4n+3 (nis a positive integer), an organic compound having a dichalcogenfive-membered ring, and an organic compound having a monochalcogensix-membered ring.
 14. A method of manufacturing a semiconductor device,comprising: (A) forming a gate electrode on a base, and then forming agate insulating layer on the base and the gate electrode; (B) forming achannel formation region and a channel formation region extension formedof an organic semiconductor material on the gate insulating layer; and(C) forming a pair of source/drain electrodes above the channelformation region extension, the method further comprising: betweenprocesses (B) and (C), forming a charge injection layer-precursor layerformed of an organic compound on the channel formation region extension,and then performing oxidation on the charge injection layer-precursorlayer to form a charge injection layer having a higher electricconductivity than the charge injection layer-precursor layer.
 15. Amethod of manufacturing a semiconductor device, comprising: (A) forminga gate electrode on a base, and then forming a gate insulating layer onthe base and the gate electrode; (B) forming a channel formation regionand a channel formation region extension formed of an organicsemiconductor material on the gate insulating layer; and (C) forming apair of source/drain electrodes above the channel formation regionextension, the method further comprising: between processes (B) and (C),forming a charge injection layer-precursor layer formed of an organiccompound on the channel formation region extension, and then performingoxidation on the charge injection layer-precursor layer to form a chargeinjection layer, wherein the organic compound includes at least oneorganic compound selected from the group including a Weitz typeoxidation-reduction based organic compound, an organic compound having acyclic structure in which the number of π electrons is 4n+3 (n is apositive integer), an organic compound having a dichalcogenfive-membered ring, and an organic compound having a monochalcogensix-membered ring.
 16. A method of manufacturing a semiconductor device,comprising: (A) forming a pair of source/drain electrodes on a base; (B)forming a channel formation region formed of an organic semiconductormaterial between the pair of source/drain electrodes and additionallyforming a channel formation region extension formed of the organicsemiconductor material above each of the source/drain electrodes; and(C) forming a gate insulating layer on the channel formation region andthe channel formation region extension, and then forming a gateelectrode on a portion of the gate insulating layer on the channelformation region, the method further comprising: between processes (A)and (B), forming a charge injection layer-precursor layer formed of anorganic compound on each of the source/drain electrodes, and thenperforming oxidation on the charge injection layer-precursor layer toform a charge injection layer having a higher electric conductivity thanthe charge injection layer-precursor layer.
 17. A method ofmanufacturing a semiconductor device, comprising: (A) forming a pair ofsource/drain electrodes on a base; (B) forming a channel formationregion formed of an organic semiconductor material between the pair ofsource/drain electrodes and additionally forming a channel formationregion extension formed of the organic semiconductor material above eachof the source/drain electrodes; and (C) forming a gate insulating layeron the channel formation region and the channel formation regionextension, and then forming a gate electrode on a portion of the gateinsulating layer on the channel formation region, the method furthercomprising: between processes (A) and (B), forming a charge injectionlayer-precursor layer formed of an organic compound on each of thesource/drain electrodes, and then performing oxidation on the chargeinjection layer-precursor layer to form a charge injection layer,wherein the organic compound includes at least one organic compoundselected from the group including a Weitz type oxidation-reduction basedorganic compound, an organic compound having a cyclic structure in whichthe number of π electrons is 4n+3 (n is a positive integer), an organiccompound having a dichalcogen five-membered ring, and an organiccompound having a monochalcogen six-membered ring.
 18. A method ofmanufacturing a semiconductor device, comprising: (A) forming a channelformation region and a channel formation region extension formed of anorganic semiconductor material on a base; (B) forming a pair ofsource/drain electrodes above the channel formation region extension;and (C) forming a gate insulating layer on the channel formation regionand the pair of source/drain electrodes, and then forming a gateelectrode on a portion of the gate insulating layer on the channelformation region, the method further comprising: between processes (A)and (B), forming a charge injection layer-precursor layer formed of anorganic compound on the channel formation region extension, and thenperforming oxidation on the charge injection layer-precursor layer toform a charge injection layer having a higher electric conductivity thanthe charge injection layer-precursor layer.
 19. A method ofmanufacturing a semiconductor device, comprising: (A) forming a channelformation region and a channel formation region extension formed of anorganic semiconductor material on a base; (B) forming a pair ofsource/drain electrodes above the channel formation region extension;and (C) forming a gate insulating layer on the channel formation regionand the pair of source/drain electrodes, and then forming a gateelectrode on a portion of the gate insulating layer on the channelformation region, the method further comprising: between processes (A)and (B), forming a charge injection layer-precursor layer formed of anorganic compound on the channel formation region extension, and thenperforming oxidation on the charge injection layer-precursor layer toform a charge injection layer, wherein the organic compound includes atleast one organic compound selected from the group including a Weitztype oxidation-reduction based organic compound, an organic compoundhaving a cyclic structure in which the number of π electrons is 4n+3 (nis a positive integer), an organic compound having a dichalcogenfive-membered ring, and an organic compound having a monochalcogensix-membered ring.
 20. The method according to claim 12, wherein theoxidation performed on the charge injection layer-precursor layer isnatural oxidation under an air atmosphere.